Scooby stumbles across Velma and Shaggy kissing, and discovers their relationship. Shaggy gets into a dilemma when Velma and Scooby fight over who he likes better, and he is forced to decide.
In the 2010 series , Velma and Shaggy have begun dating. In this new series, Velma is pushing Shaggy to be more intimate. Shaggy, however, is hesitant due to his desire to hide the relationship from Scooby until he feels confident enough to tell Scooby. This caused some tension between Shaggy and Velma. On top of that, Velma became very controlling: telling Shaggy what to eat, what to wear, even what to say. As per advice from Daphne, she increased this behavior for a brief period; she toned it down by Shaggy's request. Eventually, Scooby became aware that they were dating. Scooby's initial reaction was exactly what Shaggy had feared: anger, jealousy, and a sense of betrayal. There appeared to be some mild animosity between Scooby and Velma due to this subject. This animosity had even elevated to insults (a stark contrast from previous incarnations of characters). In the end, they gave Shaggy an ultimatum: he had to choose between them. It can be assumed that Shaggy was desperate to avoid making such a decision. Ultimately, Shaggy chose Scooby and broke up with Velma, leaving her heartbroken and humiliated. Despite bitter feelings over the breakup, Velma admitted to Scooby that she still has feelings for Shaggy. It is unclear where things will go from this point. At present, Velma is not on good terms with either Shaggy or Scooby.
As Velma and Shaggy's relationship grows, Velma realises the more and more faults of Shaggy so attempts to fix them, Velma tries to get Shaggy to stop saying the word "like" so frequently as well as to start wearing new pants.
If you grew up in the 90s you are surely familiar with Scooby-Doo and the team of teen mystery solvers – Fred, Daphne, Velma and Shaggy.